Known as a method for doping a Ga2O3-based single crystal are a method in which a dopant is added during crystal growth by the MBE (Molecular Beam Epitaxy) method or the EFG (Edge-defined Film-fed Growth) method (see. e.g., PTLs 1 and 2) and a method in which a dopant is added to a grown Ga2O3-based single crystal by ion implantation (see e.g. PTL 3). Also, a Schottky barrier diode formed of a Ga2O3-based compound semiconductor (e.g. PTL 4) is known.